Title

The impact of a weight loss program on risk factor assessment for obesity, coronary heart disease, and diabetes mellitus type 2

Date of Completion

January 2004

Keywords

Health Sciences, Nutrition

Degree

Ph.D.

Abstract

These studies were completed to assess risk factors of diabetes mellitus type 2 (DM2) and coronary heart disease (CHD) before and after a 10 wk weight loss program in a population of overweight/obese premenopausal women. The program entailed a hypocaloric diet, modified carbohydrate and protein intake, increased activity as measured by number of steps, and double blind, random assignment to carnitine supplementation or placebo. Fasting plasma lipoproteins, apolipoproteins (apos) B, CI, CIII, E, low density lipoprotein (LDL) atherogenicity, and body composition were measured at baseline and ten weeks. In a population of 80, 30% had insulin resistance and 11% had metabolic syndrome. Both waist circumference (WC) and body mass index (BMI) were positively correlated with insulin and leptin and negatively correlated with number of steps. However, WC also presented positive correlations with diastolic blood pressure (P < 0.05), plasma triglycerides (TG) (P < 0.05), and apo C111 (P < 0.05). By assessing participants' self-selected diets, we found that carbohydrate intake was positively associated with TG and apo CIII concentrations and negatively associated with LDL diameter. Participants consuming <53% of energy as carbohydrates had significantly higher intakes of fat and cholesterol but significantly lower concentrations of LDL-C and apo B than those consuming ≥53%. ^ After 10 weeks, 70 participants significantly decreased caloric intake and increased number of steps. Plasma total cholesterol, LDL-C, and TG decreased (P < 0.01) following the intervention. Likewise, apos B, CI, and E significantly decreased. Apo B concentrations were inversely correlated with plasma carnitine in those participants consuming carnitine. LDL mean particle size increased (P < 0.01) and percent of small LDL subfractions decreased. In addition, LDL oxidation measures improved; lag time increased (P < 0.01) and conjugated diene formation decreased (P < 0.01). Weight, BMI, and WC significantly decreased after 10 weeks. Percent body and trunk fat significantly decreased and percent body and trunk lean mass significantly increased. These studies support identification of early risk factors for DM2 and CHD to fully assess risk level. Once risks are identified, dietary modification and physical activity can be prescribed to improve body composition and plasma lipids. ^